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A few more things


Chris Waldrup
 

Hi Guys,

I am working on getting this little receiver up and running but noticed a
few things I wanted to ask of those more experienced.

I connected my generator and set it to 7.040 Mhz at -60 dBm then went to the
General tab and clicked on Calibration. I set the frequency in the field to
the generator frequency and clicked on start and it gave me a Frequency
Calibration Complete message. I did the same thing for amplitude, so now
the peak on the spectrum display is at -60 dBm. However the displayed
reading for the RX meter at the top right says -83.2 dBm. As I tune around
and the peak disappears the reading changes. What causes the discrepancy
between the signal meter reading and the spectrum peak's value- is the
reading an average between the signal and the noise floor?

The clicking was stopped by selecting MME under the Primary Sound Card
setup details field under Audio. Thanks Bruce for this help. I was worried
that I had to get a new soundcard for the computer (which is new, so I hate
to replace something that isn't broken).

I worked more with the Image Reject feature under DSP and I can only null it
by about 10 dB. It is sitting at about -65 dBm right now. The best null
comes with the Phase all the way to 400 at far right and the Gain all the
way to -500 at far left. The controls are at the end of their setting so I
need more range and I don't get the twitchy response that Bill mentioned. I
went back to the General tab and clicked on calibrate Image Null (above
values) and got an message that says "Error calculating image null. Please
try again."

Does this mean that the receiver is bad or is there something in the
software I need to change?

Thanks again for a great little receiver and especially for this forum that
we can get almost real time help from the designers and more experienced
users. It helps tremendously!

Chris
KD4PBJ

----- Original Message -----
From: "Chris Waldrup" <kd4pbj@...>
To: <softrock40@...>
Sent: Thursday, October 06, 2005 6:56 PM
Subject: Re: [softrock40] Re: Softrock up and running but need a little
guidance


Hi Bruce,

That fixed it! The background would pop and shift levels even with no
antenna or signal generator connected. Quite annoying when listening to a
faint signal. Now that I got that taken care of, tonight I will work on
spur nulling and checking on the amplitude level readings (did not agree
with performance verified HP signal generator when I was testing it last
night).
The computer I am using is a Dell 3.06 Ghz machine with XP and 512 MB of
RAM
so this should be fast enough.
Thanks again.

Chris
KD4PBJ
----- Original Message -----
From: "Bruce Beford" <bruce.beford@...>
To: <softrock40@...>
Sent: Thursday, October 06, 2005 6:44 AM
Subject: [softrock40] Re: Softrock up and running but need a little
guidance


Hi, Chris.

Re: The "popping sound" and shift in signal levels- (when you say
the signal level goes from -140 dBm to -50 dBm during these jumps, I
am sure you are talking about the background signal, not the output
of the signal generator itself.) This sounds like the Windows audio
driver issue that many of us have seen. Go to the Audio tab of the
PowerSDR Setup screen. Set the audio driver to MME, instead of
Windows DirectSound. Hope this helps.

73, -Bruce, N1RX

.--- In softrock40@..., "Chris Waldrup" <kd4pbj@b...>
wrote:
<snip>
Tonight I hooked it up to my 8640 generator and hear the tone
fine, but every few seconds there is a rapid succession of a few
clicks where the signal dies and then comes back. The signal
strength goes up from about -140 dBm to mid -50's. The LED does not
flicker at all during this (I had thought that the USB connector may
be loose) and I tried connecting the USB connector up to my wife's
new laptop and I get the same result. I also connected the radio up
to my antenna to rule out the generator acting funny and I get the
same result.
<snip>
Chris Waldrup
KD4PBJ





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